Fabric softening compositions suitable for providing fabric softening and static control benefits during laundering are well known in the art. Such compositions generally contain, as the softening component, a substantially water insoluble quaternary ammonium compound having two long alkyl chains.
Further, the use of various quaternized esteramines as fabric softening agents is also known in the art. U.S. Pat. No. 4,339,391 to Hoffmann, et al. for example, discloses a series of quaternized ester-amines which have utility as fabric softeners.
U.S. Pat. No. 5,296,622 discloses quaternized ester amines having fabric-softening and hydrophilicizing properties which are obtained by reaction of unsaturated fatty acids containing at least 40 mol-% trans-configured double bonds or esters thereof with alkanolamines and subsequent quaternization of the reaction products with allating agents.
WO/93/21291 to Henkel claims textile treatment agents containing as a softener, quaternary ammonium compounds with 1, 2 or 3 acyloxyalkyl groups bound to the nitrogen atom. The compounds allegedly have a low viscosity if all or some of the acyl groups are derived from unsaturated fatty acids with a least 30% in the cis form.
U.S. Pat. No. 5,023,003 to KAO discloses a softener composition which comprises at least one quaternary ammonium salt of the following formulae: ##STR1## wherein R.sup.1 and R.sup.2 each represent a hydrocarbon radical having 12-22 carbon atoms, preferably 16-22 carbon atoms and one unsaturated bond; R.sup.3 and R.sup.4 represent a methyl, ethyl or ##STR2## wherein n is an integer from 1 to 5, and Y is H or methyl; R.sup.5 and R.sup.6 each represent a hydrocarbon radical having 11-21 carbon atoms and one unsaturated bond; X represents halogen, CH.sub.3 SO.sub.4, C.sub.2 H.sub.5 SO.sub.4 ; wherein the stereoisomeric structure of the above said salt includes both the cis-isomer and the trans-isomer with the cis-isomer and the trans-isomer ratio being in the range of from 25/75 to 90/10.
U.S. Pat. No. 4,767,547 discloses fabric softening compositions containing a rapidly biodegradable quaternary ammonium softening agent of the formula: ##STR3## R.sub.1 is (CH.sub.2).sub.n --Q--T.sub.2 or T.sub.3 ; R.sub.2 is (CHO.sub.2).sub.n --Q--T.sub.4 or T.sub.5 or R.sub.3 ;
R.sub.3 is C.sub.1 -C.sub.4 alkyl; PA1 T.sub.1, T.sub.2, T.sub.3. T.sub.4, T.sub.5 are (the same or different) C.sub.12 -C.sub.22 alkyl or alkenyl; PA1 I.) a C.sub.11 -C.sub.23 substituted or unsubstituted fatty acid or mixture of fatty acids having an Iodine Value of from about 20 to about 90, and having less than about 20% trans double bonds, with PA1 II) an ether alkanolamine of the formula: ##STR7## wherein R is a C.sub.2 -C.sub.6 alkyl ether, and each of R.sub.1 and R.sub.2 is independently selected from C.sub.2 -C.sub.6 hydroxyalkyl groups, PA1 (i) Straight-Chain, Primary Alcohol Alkoxylates PA1 (ii) Straight-Chain, Secondary Alcohol Alkoxylates PA1 (iii) Alkyl Phenol Alkoxylates PA1 (iv) Olefinic Alkoxylates PA1 (v) Branched Chain Alkoxylates
n is an integer from 1 to 4; and X.sup.- is a softener-compatible anion, the composition having a pH, at 20.degree. C., of from 2.5 to 4.2 upon dilution, in de-ionized water, to a concentration of 0.5% to 1% of said rapidly biodegradable quaternary ammonium compound.
WO 94/20597 to Procter & Gamble relates to softening compounds containing diester quaternary ammonium compounds wherein the fatty acyl groups have an Iodine Value of from greater than about 5 to less than about 100, a cis-trans isomer weight ratio of greater than about 30/70 when the Iodine Value is less than about 25, the level of unsaturation being less than about 65% by weight, wherein said compounds are capable of forming concentrated aqueous compositions with concentrations greater than about 13% by weight at an Iodine Value of greater than about 10 without viscosity modifiers other than normal polar organic solvents present in the raw material of the compound or added electrolyte.
EP 0 550 361 to Stepan discloses cationic fabric treating compositions which comprises quaternary ammonium compounds which are the reaction product of a long chain fatty acid and a tertiary amine wherein the ratio of fatty acid to amine is between 1.85 and 1.4.
WO 91/01295 to Henkel discloses quaternary ammonium compounds useful as textile treatment agents which are prepared by reaction of fatty acids with alkanolamine and thereafter alkylating same to give the quaternary compounds. The esterification reaction is carried out in the presence of an acid catalyst such as hypophosphorous acid. The final product allegedly comprises mono-, di- and triester components in a ratio of 10:62:28%. There is no disclosure, however, of a process for the preparation of a final product having high diester content, i.e., greater than about 55% by weight, and low triester content, i.e., lower than about 20% by weight.
Finally, WO 94/14935 to Henkel discloses concentrated textile softener dispersions containing quaternary ammonium compounds derived from triethanolamine and containing one, two or three fatty acyloxyethyl groups. When the proportion of compounds having two fatty acyloxyethyl groups is larger than 50% by moles, these compounds allegedly have a particularly low viscosity. However, no process to achieve this level of diester was disclosed in this document, and there is no indication of the triester content of the final product.
Therefore, it is clear that the prior art discussed hereinabove does not contemplate or suggest the quaternized diester based softener composition containing high diester content and low triester content. A process for the preparation of such products is also not contemplated.
Accordingly, it is an object of the present invention to provide quaternized esteramine product having high diester content and low triester content. It is a further object of the present invention to provide a textile softening composition which comprises as a major ingredient the quaternary diester compound of the present invention. Another object of the present invention is to provide a textile softening composition which is non-yellowing and has improved softening performance and desirable textile softening properties such as improved softener biodegradability, viscosity, water absorbency, stability and the like. Finally, it is an object of the present invention to provide a hair care composition which comprises as a major ingredient the quaternary diester compound of the present invention. These and other objects are readily apparent from the following disclosure.